ABB TTF300 - Shielding Example: Ungrounded Housing; Shielding Example: Grounded Housing

TTF300 FIELD-MOUNT TEMPERATURE TRANSMITTER | OI/TTF300-EN REV. I 33
Insulated sensor measuring inset (thermocouple, mV, RTD, Ohm), transmitter housing not grounded
The shielding of the power supply cable and the shielding of the sensor connection cable are connected to one another via the
transmitter housing. The shielding is grounded at one end of the power supply cable, directly at the supply isolator / DCS input. Make
sure that the shielding is not connected to ground anywhere else.
1
Temperature sensor
2
Shielding insulated from sensor
3
Sensor connection cable
4
Shielding connected electrically via transmitter housing
5
Transmitter housing, not grounded
6
Supply voltage cable
7
Grounding point
8
Supply isolator / DCS-input
Figure 24: The shielding of the sensor connection cable and the shielding of the power supply cable are connected electrically via the transmitter housing and grounded at one end
Non-insulated sensor measuring inset (thermocouple), transmitter housing grounded
The shielding of the sensor connection cable is grounded via the grounded pressure sensor housing. This shielding of the power
supply cable is insulated from the transmitter housing.
The shielding of the power supply cable is grounded at the supply isolator / DCS input directly This shielding is insulated from the
transmitter housing. The shielding of the power supply cable and the shielding of the sensor connection cable must not be connected
to one another. Make sure that the shielding is not connected to ground anywhere else.
1
Temperature sensor
2
Shielding grounded via sensor
3
Sensor connection cable
4
Shielding insulated from transmitter housing
5
Transmitter housing, grounded
6
Shielding insulated from transmitter housing
7
Supply voltage cable
8
Grounding point
9
Supply isolator / DCS input
Figure 25: The shielding of the sensor connection cable and of the supply voltage cable are separate and each grounded on one side.